Wheel cylinder baffle construction and method of making same



Feb. 2, 1960 c. F. BRITTON 2,923,056

WHEEL CYLINDER BAFFLE CONSTRUCTION AND METHOD OF MAKING SAME 2 Sheets-Sheet 1 Filed July 22, 1955 IN VEN TOR.

CLAYTON E BRITTON BY 80L (4,. gu a/ AT TOEN E Y Feb. 2, 1960 c. F. BRITTON 2,923,056

WHEEL CYLINDER BAF'FLE CONSTRUCTION AND METHOD OF MAKING SAME Filed July 22, 1955 2 Sheets-Sheet 2 IN VEN TOR. CLAYTON F. BEITTON AT TOEN E Y United States PatentQ 2,923,056 WHEEL CYLINDER RAFFLE CONSTRUCTION AND METHOD OF MAKING SAME Clayton'F. Britton, South Bend, Ind., assignor to Bendix: Aviation Corporation, South Bend, Ind., a corporation of Delaware Application July 22, 1955, Serial No. 523,821

3 Claims. 01. 29-522 This invention relates to a wheel cylinder construction and method for making the wheel cylinder. The category of wheel cylinders considered in this invention are those wherein two oppositely-acting pistons are reciprocably received and are arranged to be spread apart or oppositely applied to actuate a brake or the like.

This invention is related to cope'nding application 350,- 560, filed April .23, 1953. The present invention has generally the same objects as the referenced application and is further intended to provide an improved method of assembly, and greater structural rigidity to the fluid motor.

One of the objects of the invention is to positively locate a passage connecting two compartments in the fluid motor in order to ensure that the passage is always 10- cated at the uppermost part of the fluid motor. This location of the passage enables improved bleeding of air on both sides of the partition or baflle. passage between the compartments is formed by notching the partition or baflle, it is possible that the baiiie can be accidentally rotated or turned angularly during assembly so that the passage separating the two compartments is no longer located at the uppermost part of the fluid motor. One of the prominent characteristics of the present invention is that the passage connecting the two compartments is always located at an optimum position regardless of the angular position assumed by thebafile during installation in the fluid motor.

An additional feature of the invention is to positively secure the baflie in place so that it cannot he accidentally dislodged by fluid pressure which is developed in the fluid motor during brake applications.

It is the aim of the present invention to permanently and positively secure the baffle within the fluid motor through methods which can be easily adapted for high scale production.

Other objects and features of the present invention willbecome apparent from a consideration of the following description which proceeds with reference to the accompanying drawings wherein:

Figure 1 shows a completed fluid motor;

Figures 2 and 3 are enlarged detail views of the encircled portions indicated in Figure 1;

Figure 4 is an end view of the fluid motor 'with the piston removed, looking from the right hand side of Figure l;

Figure 5 is a detail view of the punch used in assembling the fluid motor;

Figure 6 is a left hand end viewof Figure '5;

Figure 7 is an enlargement of the encircled portion of Figure 5;

Figure 8 is a detail view of the backup plug which supports the baffle while it is being punched; and

Figure 9 is a view of the tools used in assembling the wheel cylinder, said tools being shown in assembling location within the fluid motor.

A wheel cylinder indicated generally by reference numeral 10 (Figure 1) includes a cylinder bore 12 and When, the

two oppositely-acting pistons 14 and 16 which are arranged to anchor on the. remote ends of wheel cylinder 10. This construction is sometimes referred to as a wheel cylinder anchor since the wheel cylinder is arranged to take braking torque by virtue of engagement of the pistons with the ends of the Wheel cylinder. The wheel cylinder is divided intotwo compartments or chambers 18 and 20 by a transversely arranged partition 22 which consists of a flat disk or the like. The partition acts as a battle for the hydraulic fluid in the cylinder and is secured in the bore 12 of the wheel cylinder.

Referring to Figures 1,2, 3, and 4, an annular groove 24 is machined in the cylinder bore around the entire inner diameter of the cylinder bore. A cutter (not shown) of radius r (Figure 4), is then used to form a lunular notch 26 (Figures 1 and 3) which widens the groove 24 along an'arcuatei segment thereof. Notch 26, as indicated in Figure 3, is also considerably greater in Width than the partition 22. The notch 26 is of equal or greater depth than groove 24 to form a passage 28 which connects the two compartments or chambers 18 and 20.

'An, inlet port 30 and bleed port 32 are located in compartment 18 which is 'onthe left hand'side of the parti tion 22 in Figure-1.

The wheel cylinder is arranged in the position shown in Figure 1 when thebrake is assembled. It will be noted that the notch 26 is located at the uppermost part of the cylinder bore when the fluid motor is positioned as shown in Figure 1. This is particularly significant since 'eflicient bleeding of the'brake requires thorough purging of air on either side of the compartment, and this necessitates circulating the fluid so that it leaves compartment 20 at the highest level thereof. Any entrained air bubbles which may have collected in the compartmentv 20 are thus carried out of the compartments and leave 'the wheel cylinder via bleed port 32.

It will be, noted that this proper location of the pas-. sage is established by machining the notch 26 in the cylinder bore; thus, its. location is independent of the angular position of the partition 22.

'In assembling the partition within the fluid motor, a flat disk is inserted in the cylinder bore 12 and a locating plug 36 is inserted in the left hand side of the fluid motor (Figure 9). While the fluid motor is held in a fixture, end 34 of plug 36 is then brought into contact with the left hand side of the partition 22 (referring to Figure 9). A punch 38 (Figures 5 and 9) is then thrust into the right hand side of the fluid motor. At the face 40 (Figures 5, 6, and 7) of the punch, there is formed a corner 42 which is in the shape of an incomplete annulus indicated in Figure 6. The corner or ridge 42 contacts the right hand side of the partition 22 and when it is driven against the face of the partition by a suitable tool (hammer or the like), the right hand face of the partition is indented with a recess 44 corresponding in shape to that of the corner 42. A bead 46 (Figure 2) at the edge of the partition is extruded into groove 24, thus mortising the partition 22 and cylinder bore together. The head 46'is also an incomplete annu- 'lus corresponding in length to that of the ridge 42 on the punch. The partition 22 is thus securely held in place within the bore 12 of the fluid motor.

The general purpose of the partition or baflde 22 is to prevent brake clicking which arises from sudden slamming of the pistons into the anchoring position wherein they contact the ends of the fluid motor. This is accomplished in the following manner: piston 14 is associated with the actuatable end of the primary shoe of a Duo- Servo brake and piston 16 is associated with the actuatable end of the secondary shoe. .When the brake is applied, fluid pressure is built up at a faster rate in com- The primary shoe is thus fully applied before the piston 16 moves appreciably away from its anchoring position. If the piston 16 should move from anchored position, the impact of returning it to anchored position is. cushioned by the restricted rate of fluid transfer through the passage 28 from compartment 20 to compartment 18. This principle. is fully explained in copending application No. 350,560, previously identified in this disclosure.

As indicated from Figures 2 and 6, the joint formed between the partition 22 and cylinder bore 12 is obtained by extending an incomplete annular bead of material into the groove 24. The angular portion a indicated in Figure 6 is not extruded in a radial direction. Thus, the fastening operation does not seal the passage 28 which is formed between notch 26 and the outer edge of the partition within the angle a. The bead 46 (Figure 2) does, however, form a seal between the partition and the bore 12 so that fluid can pass across the partition only at the passage 28 at the top of the cylinder bore. It is thus possible to control the restriction while maintaining its proper location.

Although a single selected embodiment of the invention has been chosen to illustrate the invention, it will be apparent to those skilled in the art that various modifications and changes may be made without departing from the underlying principles thereof. I intend therefore to include within the scope of the following claims, all such variations and modifications which can be expected to occur to those skilled in the art.

I claim:

1. In a method of making wheel cylinders, the steps which comprise: providing a wheel cylinder having a longitudinally extending cylinder bore, machining an annular groove in the cylinder bore approximately midway between the ends thereof, cutting an arcuate notch of greater width than said groove along a segment of said groove and located at the uppermost portion of said cylinder bore when the wheel cylinder is in operating position, locating a baflle within said cylinder bore with the outer edge thereof in alignment with said groove, simultaneously backing up and punching said baflle only along the periphery adjacent the narrower'width portion of the groove whereby material is extruded into said narrower width groove portion to fixedly locate the battle transversely within said bore while maintaining a clearance between said bafl le and arcuate notch at the uppermost portion of said cylinder bore thereby providing a restricted passage across said bafllc.

2. In a method for making wheel cylinders, the steps including: machining an annular groove in the wheel cylinder bore, forming a notch of greater width than said groove along a segment thereof and at the uppermost level of said cylinder bore, locating a partition transversely within said cylinder bore with the edges thereof in alignment with said groove, and punching only the margin of said partition adjacent the narrow width portion of said groove to extrude metal within said narrower width groove portion while maintaining clearance between said partition and notch of greater width to thereby provide fluid transfer across said partition at the region between said partition and notch.

3. In a method of making fluid motors, the steps including;- forming an annular groove in the wall ofthe cylinder, machining a notch along a segment of said groove to increase the Width thereof, transversely locating a partition within said cylinder, and punching only the marginal portion thereof adjacent the narrower width portion of said groove to extrude material into said narrower width portion of said groove to sealingly mortise the partition and cylinder bore and provide fluid passage across said partition through the clearance between the partition and said notch.

References Cited in the file of this patent UNITED STATES PATENTS Shank Nov. 1, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 2,923,056 February 2 1960 Clayton F. Britten It is hereby certified that error eppears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3 line l2 for "extending" read extruding line 43, after "periphery" insert thereof Signed and sealed this 27th day of September 1960,

(SEAL) Attest:

KARL H. AXL INE ROBERT (J. WATSON Attesting Ofiicer Commissioner of Patents 

